While you can't just put some inexperienced fan and expect success, I've often wondered if the effect of NBA head coaching is overrated. (It is definitely WAY overrated in MLB). No coach is going to do poorly coaching the Warriors. Similarly no coach is going to make the Nets successful. Ultimately coaches don't play and there are some coaches that seem to do nothing but manage player minutes. With that in mind, let's group coaches using letter grades: A: Widely considered a top coach B: Above average coach B-/C+: Average or "Replacement Level" coach C: Below average coach D: Widely considered a bad coach F: Totally clueless coach Of current coaches, what are examples of A, B, C and D grade coaches? And honestly, how much difference would it make if you swapped a D coach with an A coach and vice versa?